Modulation of prostaglandin metabolism is at the center of current anti-inflammatory therapies. NSAIDs and COX-2 inhibitors block the activity of cyclooxygenases and their ability to convert arachidonic acid (AA) into prostaglandin (PG) H2. PGH2 can be subsequently metabolized by terminal prostaglandin synthases to the corresponding biologically active PGs, namely, PGI2, thromboxane (Tx) A2, PGD2, PGF2α, and PGE2. A combination of pharmacological, genetic, and neutralizing antibody approaches demonstrates the importance of PGE2 in inflammation. In many respects, disruption of PGE2-dependent signalling in animal models of inflammation can be as effective as treatment with NSAIDs or COX-2 inhibitors. The conversion of PGH2 to PGE2 by prostaglandin E synthases (PGES) may therefore represent a pivotal step in the propagation of inflammatory stimuli.
Microsomal prostaglandin E synthase-1 (mPGES-1) is an inducible PGES after exposure to pro-inflammatory stimuli. mPGES-1 is induced in the periphery and in the CNS by inflammation and represents therefore a novel target for acute and chronic inflammatory disorders. The rationale for the development of specific mPGES-1 inhibitors revolves around the hypothesis that the therapeutic utility of NSAIDs and Cox-2 inhibitors would be largely due to inhibition of pro-inflammatory PGE2 while the side effect profile would be largely due to inhibition of other prostaglandins.
The present invention is directed to novel compounds that are selective inhibitors of the microsomal prostaglandin E synthase-1 enzyme and would therefore be useful for the treatment of pain and inflammation in a variety of diseases or conditions, such as osteoarthritis, rheumatoid arthritis and acute or chronic pain. Furthermore, by selectively inhibiting the pro-inflammatory PGE2, it is believed the compounds of the invention would have a reduced potential for side effects associated with the inhibition of other prostaglandins by conventional non-steroidal anti-inflammatory drugs, such as gastrointestinal and renal toxicity.